The present invention relates to the testing of an individual for immune reactions to ingestants, including foods, and in particular, to a unique, simple and relatively inexpensive device and method for determining food hypersensitivity and for identifying different types of immune reactions against specific foods and chemicals.
There are four generally recognized types of immune responses to foods which are commonly referred to as Gell-Coombs Types I, II, III and IV. Type I is characterized by the involvement of immunoglobulin "E" (IgE) antibodies which are produced by specific B-lymphocytes in response to the particular food. It was known that sensitized IgE antibodies were resident under the skin, as well as many other tissues and organs. Foods producing a Type I immune response could be tested through the skin by injecting into cutaneous layers of skin an aqueous solution of the food producing the Type I response. Prick tests could also be employed with aqueous food solutions. Therefore, food producing a Type I reaction could be tested intradermally. The immune response could be detected for a given food if redness or swelling appeared at the injection or prick test site. Type I responses may also be tested by Raido allergo sorbent testing (RAST).
Gell-Coombs Types II and III are characterized by the involvement of immunoglobulin "G" (IgG), immunoglobulin "M" (IgM), and some special IgE antibodies. Heretofore, intradermal tests were unable to produce a reliable immune response in the skin to foods producing a Type II or Type III immune response. This was largely true for the fat-soluble foods producing a Type II or Type III response. Fat-soluble foods being insoluble in water and, of course, not adaptable to the introduction through or into the skin in aqueous solution by means of a prick test or injection. This was also true for water-soluble foods producing a Type II or Type III immune response.
Consequently, when an individual was suspected clinically to have a Type II or Type III reaction to a particular food, an elimination diet was typically prescribed to detect the suspect food. An elimination diet involves initially restricting a patient's intake to foods which usually are hyporeactive. Pure foods are then introduced one-by-one as challenges into the diet to assess whether the person is hypersensitive to the added foods. The elimination diet can also be used for the detection of Type I immune responses.
The problems with the elimination diet are multiple. First, the elimination diet depends upon the patient experiencing discomfort or obvious organ dysfunction, usually a subjective evaluation. Any immune responses not producing discomfort or obvious organ dysfunction would not be detected by the elimination diet technique. Second, the elimination diet will detect discomforts or organ dysfunctions which are not related to immune responses to foods. For instance, the individual may have duodenal ulcers, colitis, gout, or gall bladder problems which produce discomfort when certain foods are eaten. These discomforts and dysfunctions are, however, not related to the individuals immune responses to the particular food. Therefore, the elimination diet may have misleading results. Thirdly, the elimination diet is very time consuming. An individual having to be on the elimination diet for several months is not at all unusual.
Finally, human weaknesses undermine accurate determination of an individual's immune response to given foods. It is difficult for some patients to eliminate from their diets certain foods to which they may be sensitive. Such foods are widespread in our food supply; they include chicken, beef, pork, chocolate, eggs, milk, coffee, peanuts, tomatoes and wheat, to name a few. Immune responses to foods not on the patient's diet can mask immune responses to foods under study or mislead the practitioner into believing that a food under study produces an immune response when in fact the food produces no such response.
If the elimination diet fails to lead to the detection of an immune response to a given food, there are a number of alternative tests which can be employed. For Type II immune responses, the hemaglutinations test, the complement depletion test, or a tissue biopsy can be performed. All of these tests are indirect, time-consuming, expensive and often inaccurate. These same tests can also be used to detect a Type III reaction. In addition, the Raji-Cell Test or a nephelometry test can be used to detect a Type III reaction. These tests are also time-consuming, expensive and often inaccurate because of technical intracacies.
The Type IV Gell-Coombs reaction involves sensitized lymphocytes or T-cells which respond to a specific food and which are believed to be at least as specific as an antibody to the food producing the immune response. Two tests have heretofore been available, namely, the migration inhibition factor test and the lymphoblastogenesis test. These tests are extremely expensive, each food presently costing approximately $2,000 to test. The tests are time-consuming as well, taking approximately 3-4 weeks.
As should be apparent, the diagnosis and treatment of immune reactions to ingestants has involved relatively expensive and complicated diagnostic tests. The laboratory tests are sophisticated and impractical for use in the average office facility. There has been a longfelt and unfulfilled need for a relatively simple, accurate, and inexpensive test which may be readily used by the practitioner.